What Does the Engine Oil Grade Mean?

[Beau]

Automotive engine oil grades represent the viscosity and quality of the oil. Taking "15W-40, 5W-40" as an example: 1. The meaning of the letter "W": "W" stands for Winter. The smaller the number before it, the better the oil's low-temperature fluidity, indicating a lower usable environmental temperature and better protection for the engine during cold starts. For example, 5W represents resistance to external low temperatures of -30°C, while 20W resists low temperatures of -15°C. 2. The meaning of the number after the letter "W": The number after "W" represents the kinematic viscosity of the oil at 100°C. The higher the number, the higher the viscosity. 40 indicates that the kinematic viscosity standard at 100°C is between 12.5mm²/s and 16.3mm²/s.

[SanEmersyn]

As a car enthusiast, I've done quite a bit of research on engine oil grades. Take the common SAE 5W-30 for example: the '5W' indicates smooth oil flow in low temperatures—the smaller the number, the easier cold starts are, like 0W performing well in sub-zero conditions. The '30' denotes high-temperature viscosity; higher numbers mean better engine protection against wear when hot. Choosing the right grade depends on several factors: climate plays a big role—folks up north should opt for lower W grades like 5W for harsh winters, while southern regions suit W10 or above. Engine type is also crucial: newer cars often use fuel-efficient grades like 0W-20 for economy, whereas older vehicles need higher viscosity to prevent leaks. The manual's recommended grade is the gold standard—using the wrong oil can increase fuel consumption or damage the engine. I always check during regular oil changes to ensure smooth operation and longevity.

[Gollum]

My experience of frequent driving tells me that oil viscosity grades must be taken seriously. For example, in 5W-40, the W stands for winter characteristics, with 5W offering good fluidity in cold weather for quick starts; the 40 represents high-temperature protection—the higher the number, the thicker the oil. Always follow the user manual to choose the right one, and don’t be misled by repair shops trying to save money with unsuitable oil. Climate matters too: use W5 or W0 in winter for easier driving, and opt for a higher second number (20 or above) in summer for added safety. The right grade can make the engine quieter with less noise and even slightly improve fuel efficiency; after switching to 0W-30, I noticed smoother acceleration. Regular maintenance keeps the engine in good shape, preventing small issues from turning into costly repairs.

[GrantFitz]

When I first started with car maintenance, the oil grades were confusing. Actually, those numbers like 5W-30: W stands for winter properties, the smaller number means better flow in cold weather; the larger number prevents overheating in hot weather. I learned to check the manual myself to ensure I don't buy the wrong one. Choosing the right grade avoids engine problems, it's simple and easy to check every time you change the oil.

[RileyRose]

With years of driving experience, I've learned that engine oil grades are not to be taken lightly. For example, in 10W-40, the 10W indicates low-temperature adaptability, while the 40 signifies strong high-temperature protection. I've encountered cases where novices used the wrong oil, leading to premature engine failure. In cold regions, prioritize lower W grades like 5W or 0W, while in hot areas, use higher second numbers to prevent overheating. Older vehicles require higher viscosity to control oil leaks, but always verify that maintenance shop recommendations match your car. Fuel-efficient grades suit new cars but must comply with specifications. I always stick to the manual's recommendations, ensuring my car's performance remains durable and reliable.